By that logic, do you believe that if we come to know that our enemy is really evil then its okay not to love them? I don't remember that command coming with this qualification...in fact the command seems to presume that the enemy is indeed evil ("those who wrong you") but still our response should be to do good to them and love them. I guess we don't need to follow God's example on this particular point, but just do as He says?
According to Revelation 6:9-11 there are souls looking forward to God judging their enemies.
Revelation 6:9-11
9When the Lamb broke the fifth seal, I saw underneath the altar the souls of those who had been slain because of the word of God, and because of the testimony which they had maintained; 10and they cried out with a loud voice, saying, “How long, O Lord, holy and true, will You refrain from judging and avenging our blood on those who dwell on the earth?” 11And there was given to each of them a white robe; and they were told that they should rest for a little while longer, until the number of their fellow servants and their brethren who were to be killed even as they had been, would be completed also.
God has sworn that he will repay.
Romans 12:19
19 Do not take revenge, my friends, but leave room for God's wrath, for it is written: "It is mine to avenge; I will repay," says the Lord.
So we wil rejoice in God's judgement on the wicked. His judgements are holy and his people will rejoice in the goodness of them. Hell is just punishment for the wicked and all of heaven will glorify God for his judgement.